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#include <Alib.h>
#include <stdio.h>
void DrawLine (w, x1, y1, x2, y2, zinfo)
AWindow *w;
int x1, y1, x2, y2;
ZInfo *zinfo; {
register int t;
register Edge *e, *e1;
zinfo->next = NotAnElement;
if (ClipLine (w, &x1, &y1, &x2, &y2))
return;
if (y1 > y2) {
t = x1;
x1 = x2;
x2 = t;
t = y1;
y1 = y2;
y2 = t;
}
if ((x1 == x2) || (y1 == y2)) {
if (w->EPTop >= w->EPSize - 1) {
fprintf (stderr, "Edge Pool Overflow\n");
return;
}
e = &(w->edgePool[(w->EPTop)++]);
e1 = &(w->edgePool[(w->EPTop)++]);
e->y2 = e1->y2 = y2 + 1;
#ifdef FLOAT_SLOPE
if (x1 == x2)
e->x1 = e1->x1 = x1;
else {
e->x1 = x1;
e1->x1 = x2;
}
e->Dx = e1->Dx = 0;
#else
if (x1 == x2)
e->x1 = e1->x1 = x1 << 16;
else {
e->x1 = x1 << 16;
e1->x1 = x2 << 16;
}
e->Dx = e1->Dx = 0;
#endif
e->p = e1->p = zinfo;
e1->nexte = w->edges[y1].head;
e->nexte = e1;
w->edges[y1].head = e;
}
/*
* A non-trivial case. The has a slope that is non-zero and not infinity.
* We will need one edge entry to hang off the line list at the strting y
* value of the line. We will also pre-allocate two edge entries to be used
* as the line'e edges during the EdgeTableToScanLine procedure. By our own
* convention, we'll place them in the two edge pool entries immediately
* following the line information entry.
*/
else {
if (w->EPTop >= w->EPSize - 2) {
fprintf (stderr, "Edge Pool Overflow\n");
return;
}
e = &(w->edgePool[(w->EPTop)++]);
w->EPTop += 2;
e->y2 = y2;
#ifdef FLOAT_SLOPE
e->x1 = x1;
e->Dx = (x2 - x1) / (y2 - y1);
#else
e->x1 = x1 << 16;
e->Dx = ((x2 - x1) << 16) / (y2 - y1);
#endif
e->p = (e+1)->p = (e+2)->p = zinfo;
e->nexte = w->lines[y1].head;
w->lines[y1].head = e;
}
if (y1 < w->ymin)
w->ymin = y1;
if (y2 > w->ymax)
w->ymax = y2;
}
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